Boring tool



Aug. l, 1939.

E. l.. sHAw 2,168,176

BORING TOOL Fild sept. 15, 195s "wveniw E. L. SHAW Patented Aug. l, 1939 s 2.168.116 Bouma *'roor.

I Edward -I...Sln|.w, Brookline, Mass., asslgnor to Shawlock, Inc., Boston, Mass., a corporation of usetts n Application' September 15, 1936,' Serial No. 100,849

particularly to a tool forA boring taper holes.

, Holes which are respectively -of uniform diameter for a portion of the depth thereof and then taper outwardly at the bottom are particularly useful for doweling purposes as in the manufacture of furniture Various tools which have been devised for boring these holes are usually quite complex, expensive to manufacture and of such delicate construction as to be unable to withstand hard usage, The primary object of my invention is to.

produce an improved taper hole boring tool wherein these objections are eliminated.

My improved tool embodies primarily a main supporting shank having the shank of the cutter extending into a bore therein and supported directly against the walls of such bore. Other means is provided within and exteriorlyof thebore for causing the cutter to rock laterally during its forward movement whereby to cut a tapering hole. Such construction is relatively simple and provides an extremely rugged support for the cutter.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, wherein- Fig. l is an elevation of my improved boring tool. I

Fig. 2 is a vertical partial section therethrough, taken on line -2 of Fig. 1, and showing a hole partially bored thereby.

Fig. 3 is a. like View substantially in full section showing the hole completed.

Fig. 4 is a sectional view taken on line 4-4 of Fig. 8.

Figs. 5 and 6 are cross sections taken on lines 5 5 and 6 6 of Fig. 3.

The tool as illustrated in thedrawing-comprises l a main shank or spindle yil) having a. bore i2 therein open at the forward end of vthe shank, the shank being conveniently constructed of two parts Y including a tube i3 pinned at I4 to the main shank body. The cutter or bit` i5, which forms the subject mattei` of my co-pending application, `Serial No. 212,629, led June 9, 1938, isthreaded at I i into a shank portion Il extending into the bore I2. 'Ihe mouth of the bore I2 is preferably square in cross section, as shown in Fig. 6, and the insponding size and shape, thearrangement being such that two diametrically opposed walls `I9 are fiat and parallel and in continuous fiat ensagement with the shank portion Il adJacent follows: termediate portion of the cutter shank Il which cooperates therewith is substantially of corre#` (Cl. 145-124) This invention relates to boring tools and moreto and rearwardly of the mouth of the bore see Fig. 4) while. the other' two opposedwalls 2t have a limited but constant engagement with the shank-portion i8 adjacent to the mouth of .the bore (see Fig. 3) permitting vthe cutter to rock 5 `laterally a slight amountto the position shown in. Fig. 3. During such rocking movement the cutter shank rocks on a transversely extending fulcrum Contact with the wall Ziljat the right in Fig. 3. The stein of the shank 'i8 which is within the 10 bore i2 has one wall 2li at and parallelwith the longitudinal axis of the shank and the opposite wall h of the shank isinclinedv inwardly from a. point adjacent to the open end of the bore i2,

the vextreme rearward end .portion 2i of the shank l5 being cut away to provide parallel sides as indicated in Fig. 3. A pin 22 extending transversely into the. tube i3 and cutter shank i3 holds the latter within the former.

A sleeve 2d mounted to slide on the tube i3. is 20 normally forced forwardly by a spring 25 on the tube rearwardly of the sleeve. A continuation 25 ofthe sleeve 2d, with a thrust washer 2l therebevided with an inner annular rib cooperating with a resilient packing 36 on the sleeve 2S to limit forward movement of the inner sleeves and member 28 under the action of the spring 25, the packing serving to absorb lubrication.

The extreme inner end 2i of the cutter shank may Aabut against the main shank body piece which carriesthe threaded stud 42, as illustrated in Fig. 3, or the shouldered portion-thereof may abut against the outer end of the tube i3, whereby to take the end thrust of the cutter. A pin or block 38 carried by the sleeve 24 extends trans-v versely through'slots 39in 'the tube i3 and is. provided with a slot 40 therethrough and through which extends the inclined end 2| of the cutter shank.

The operation-of the tool is substantially as The tool is supported in a socket threaded onto the stud42. In the normal position ,of the tool (Fig. 1|), `the cutter projects outwardly beyond the work engaging member 28 and thev flat 'and parallel surface MI'l of the shank i8 is in full shock and provide 35,

' at three sides thereof. In the boring operation this projecting portion of the cutter preliminarily bores a cylindrical hole (Fig. 2). When the member 28 comes in contact with the work W further forward movement'of this member, of the sleeves 26 and 24 and of the block 31 is arrested. Continued forward movement of the tool against the action of the spring 25 causes the inc1ined.por tion 2| of the cutter shank to move downwardly through the block andv such movement causes the cutter to rock laterally in a manner'gradually moving the cutting body to one side and boring Aa tapering hole as the cutter rotates and moves forwardly. The inclined wall 20h of the shank permits such movement and the at and parallel surfaces 2U and MlB thereupon separate as illustrated in Fig. 3. It will be apparent that during this movement and the' resulting cutting action, the entire shank I8 within the bore is firmly sup-- ported in two directions in the main shank I by a,

continuous fiat and parallel contact with the walls I9 and is also preferably supported`on both surfaces 28 at the forward end of the main shank or spindle I0. The arrangement as illustrated, therefore, provides surface support for the tool at all four sides of the shank I8 during the cutting operation whereby firmly backing up the tool against side thrusts caused by the outward lateral movement of the cutter as it is moved forwardly. It will be readily apparent that such construction .provides a firmer support for the cutter than have constructions heretofore known Vand which have depended on pivot pins for taking these side thrusts. 'This tool will continue to do accurate boring since the cutter shank has no pivotal points subject to wear with resulting chatter and displacement as is the case when using pivot pins, it being apparent that a very small amount of such looseness will seriouslyA affect the tool and its ef flciency. Furthermore, the several parts of the tool are relatively simple to manufacture and assemble and they are so related as to provide a more compact and rugged tool for the purpose described.

Having thus described my invention, what 1 claim as new and desire to secure by Letters Patent of the United States ist' ,f

and extending rearwardly thereof and a cooperating intermediate wall adjacent to said end, a cutter shank including a stem extending into and supported within the bore by surface contact with said parallel walls and a transversely extending fulcrum contact with the intermediate 10 wall, a sleeve slidable on said main shank, a spring normally urging the sleeve forwardly, and means carried by the sleeve and cooperating with said Y stem for causing the cutter shank to rock laterally on said fulcrum contact between and parallel with said opposing walls during forward movement thereof in the boring operation and while the cutter shank remains in supporting surface contact With said parallel walls and in fulcrum contact with the intermediate wall, the stem having clearance at a. point spaced from said fulcrum contact within the -bore permitting said rocking of the cutter shank.

2. A taper hole boring tool comprising a main shank having a, bore therein open at the forward end of the shank, the bore being rectangular in cross section and providing four inwardly facing wall surfaces adjacent to said end, two of said surfaces being fiat and parallel 'and extending rearwardly from said end of the bore, a'cutter 30 shank including a stem supported within the bore by cooperating nat and parallel surfaces thereon in surface contact with the first-named parallel surfaces, thel portion of the stem adjacent to said forward end of the bore being of cross sectional shape substantially corresponding to that of said end of thel bore and the stem having such limited contact with the other two walls of the bore at its said end as to permit lateral rocking movement' of the cutter shank about said end of the bore in aI 40 direction keeping said flat and parallel surfaces in contact during such movement, and means for causing the cutter Ashank to thus rock during forward movement thereof in the boring operation,

the stem having clearance within the bore at a point spaced from said fulcrum contact permit! ting said rocking movement.

EDWARD L. SHAW. 

